1. Field of the Invention
The present invention relates to a mobile power supply device; more particularly, the present invention relates to a mobile power supply device with an expansion interface.
2. Description of the Related Art
As technology develops, a major trend in the development of electronic devices is portability. Many manufacturers conduct research and development on portable electronic products, and the most important portable electronic product in the current market is the smartphone.
Currently, the smartphone is limited in size, weight, and appearance; therefore, the smartphone cannot include too many expansion slots or interfaces. Generally, a smartphone usually has only two expansion interfaces, namely, a Subscriber Identity Module (SIM card) slot, and an external power supply input interface (such as a Micro Universal Serial Bus interface); therefore, the smartphone cannot connect to many additional external devices due to the different connection requirements.
In addition, most current users of the smartphone also use a mobile power supply device with the smartphone to charge the smartphone when the smartphone is out of electricity. However, currently, the mobile power supply device is used only as a standby power supply; the mobile power supply device does not include any other functions except charging. Since the mobile power supply device is increasingly popular and is becoming essential equipment for the smartphone user, the external connecting function of the electronic device should be expanded via the mobile power supply device to allow further variety in the application of the mobile power supply device.